The inner diameter is 4" and the outer diameter is 5.5".
Answered on Tuesday, December 29, 2015 by Erin Killeen
Bulbrite 775700 LEDMAG4/TRWH LED Retrofit ELEVA Downlight System - 4” TRIM ROUND - WHITE\
https://www.shineretrofits.com/bulbrite-775700-ledmag4-trwh-led-retrofit-eleva-downlight-system-4-trim-round-white.htmlBulbrite 775700 LEDMAG4/TRWH
4” TRIM ROUND - WHITE